A typical oxygenating process is the LD process in which a long tube, called a lance, is used to conduct high pressure oxygen onto the surface of molten iron in a converter. A typical lance may be approximately seventy five feet in length, or thereabout and has a nozzle close to the molten iron that is usually made of copper.
The oxygen lance nozzle is subject to very high temperatures, in excess of 2000.degree. C. when operating in a converter vessel, and its survival is due solely to the cooling arrangement utilized to reduce the temperature of the nozzle. The cooling arrangement conventionally applied to the lance nozzle typically included water jackets around the oxygen supply bore; these jackets defined annular water conduits for the inlet and outlet of cooling water.
In order for the cooling water to have an appreciable effect it was necessary that the copper walls between the surface of the lance tip and the cooling water be relatively thin. However, the copper walls are eroded during operation, with the possibility that dangerous water ingress into the converter became highly probable. This danger is compounded by the fact that the cooling water is supplied at relatively high pressure to obtain the necessary transfer of heat.